<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en">
<head>
  <meta http-equiv="Content-Type" content="text/html;charset=UTF-8">
  <title>Document</title>
</head>
<body>
  <select>
        <option value="zs">中山</option>
        <option value="gz">广州</option>
        <option value="zh">深圳</option>
        <option value="zh">珠海</option>
  </select>
        <script type="text/javascript">
              //取得<select>元素节点下的子元素的个数
              //var selectElement = document.getElementsByTagName("select")[0];
              //var size = selectElement.childNodes.length;
              //alert("select下共有"+size+"个元素");
              
              //取得“中山”字符串
              //var selectElement = document.getElementsByTagName("select")[0];
              //var zsElement = selectElement.firstChild;
              //var zs = zsElement.innerHTML;
              //alert(zs);
              
              //取得"广州"字符串
              //var selectElement = document.getElementsByTagName("select")[0];
              //var zsElement = selectElement.firstChild;
              //var gzElement = zsElement.nextSibling;
              //var gz = gzElement.innerHTML;
              //alert(gz);
              
              //取得"珠海"字符串
              //var selectElement = document.getElementsByTagName("select")[0];
              //var zhElement = selectElement.lastChild;
              //var zh = zhElement.innerHTML;
              //alert(zh);
              
              //取得"深圳"字符串
              //var selectElement = document.getElementsByTagName("select")[0];
              //var zhElement = selectElement.lastChild;
              //var szElement = zhElement.previousSibling;
              //var sz = szElement.innerHTML;
              //alert(sz);
              
              //删除"广州"元素
              var gzElement = document.getElementsByTagName("option")[1];
              var selectElement = gzElement.parentNode; 
              selectElement.removeChild(gzElement);
              
              
        </script>
</body>
</html>